Low-resistance tunnel magnetoresistive effect element, and manufacturing method, testing method and testing apparatus for the element

A tunnel magnetoresistive effect element comprising:

• a tunnel barrier layer formed primarily of a metal oxide;
• and
• two ferromagnetic layers stacked so as to sandwich said tunnel barrier layer,
• said tunnel barrier layer including many electric charge sites, and
• electric popping output voltage due to the presence of said many electric charge sites occurring when a bias voltage is applied for 5 microseconds or more in a direction perpendicular to a surface of said tunnel barrier layer with said tunnel magnetoresistive effect element magnetically saturated.

A thin-film magnetic head comprising:

• at least one tunnel magnetoresistive effect element as data reading means comprising:
• a tunnel barrier layer formed primarily of a metal oxide;
• and
• two ferromagnetic layers stacked so as to sandwich said tunnel barrier layer,
• said tunnel barrier layer including many electric charge sites, and
• a density n of said many electric charge sites in said tunnel barrier layer and a mobility μ of electrons trapped due to said many electric charge sites satisfying a relationship expressed by:
• 0<(ns1−1−ns2−1)−1·(μ0−μ)·(nμ)−1<0.2
• where ns1 and ns2 are densities of tunnel electrons when an element resistance is a minimum and maximum respectively during reading signals and μ0 is the mobility of electrons when not trapped;
• and
• at least one inductive write head element as data writing means.

A thin-film magnetic head comprising:

• at least one tunnel magnetoresistive effect element as data reading means comprising:
• a tunnel barrier layer formed primarily of a metal oxide;
• and
• two ferromagnetic layers stacked so as to sandwich said tunnel barrier layer,
• said tunnel barrier layer including many electric charge sites, and
• electric popping output voltage due to the presence of said many electric charge sites occurring when a bias voltage is applied for 5 microseconds or more in a direction perpendicular to a surface of said tunnel barrier layer with said tunnel magnetoresistive effect element magnetically saturated;
• and
• at least one inductive write head element as data writing means.

A head gimbal assembly comprising:

• a thin-film magnetic head comprising:
• at least one tunnel magnetoresistive effect element as data reading means comprising:
• a tunnel barrier layer formed primarily of a metal oxide;
• and
• two ferromagnetic layers stacked so as to sandwich said tunnel barrier layer,
• said tunnel barrier layer including many electric charge sites, and
• a density n of said many electric charge sites in said tunnel barrier layer and a mobility μ of electrons trapped due to said many electric charge sites satisfying a relationship expressed by:
• 0<(ns1−1−ns2−1)−1·(μ0−μ)·(nμ)−1<0.2
• where ns1 and ns2 are densities of tunnel electrons when an element resistance is a minimum and maximum respectively during reading signals and μ0 is the mobility of electrons when not trapped;
• and
• at least one inductive write head element as data writing means;
• trace conductors for supplying currents to said at least one tunnel magnetoresistive effect element and said at least one inductive write head element;
• and
• a support mechanism which supports said thin-film magnetic head.

A head gimbal assembly comprising:

• a thin-film magnetic head comprising:
• at least one tunnel magnetoresistive effect element as data reading means comprising:
• a tunnel barrier layer formed primarily of a metal oxide;
• and
• two ferromagnetic layers stacked so as to sandwich said tunnel barrier layer,
• said tunnel barrier layer including many electric charge sites, and
• electric popping output voltage due to the presence of said many electric charge sites occurring when a bias voltage is applied for 5 microseconds or more in a direction perpendicular to a surface of said tunnel barrier layer with said tunnel magnetoresistive effect element magnetically saturated;
• and
• at least one inductive write head element as data writing means;
• trace conductors for supplying currents to said at least one tunnel magnetoresistive effect element and said at least one inductive write head element;
• and
• a support mechanism which supports said thin-film magnetic head.

A magnetic disk drive apparatus comprising:

• at least one head gimbal assembly comprising:
• a thin-film magnetic head comprising:
• at least one tunnel magnetoresistive effect element as data reading means comprising:
• a tunnel barrier layer formed primarily of a metal oxide;
• and
• two ferromagnetic layers stacked so as to sandwich said tunnel barrier layer,
• said tunnel barrier layer including many electric charge sites, and
• a density n of said many electric charge sites in said tunnel barrier layer and a mobility μ of electrons trapped due to said many electric charge sites satisfying a relationship expressed by:
• 0<(ns1−1−ns2−1)−1·(μ0−μ)·(nμ)−1<0.2
• where ns1 and ns2 are densities of tunnel electrons when an element resistance is a minimum and maximum respectively during reading signals and μ0 is the mobility of electrons when not trapped;
• and
• at least one inductive write head element as data writing means;
• trace conductors for supplying currents to said at least one tunnel magnetoresistive effect element and said at least one inductive write head element;
• and
• a support mechanism which supports said thin-film magnetic head;
• at least one magnetic disk;
• and
• a recording/reproducing circuit for controlling reading and writing operations by said at least one tunnel magnetoresistive effect element and said at least one inductive write head element.

A magnetic disk drive apparatus comprising:

• at least one head gimbal assembly comprising:
• a thin-film magnetic head comprising:
• at least one tunnel magnetoresistive effect element as data reading means comprising:
• a tunnel barrier layer formed primarily of a metal oxide;
• and
• two ferromagnetic layers stacked so as to sandwich said tunnel barrier layer,
• said tunnel barrier layer including many electric charge sites, and
• electric popping output voltage due to the presence of said many electric charge sites occurring when a bias voltage is applied for 5 microseconds or more in a direction perpendicular to a surface of said tunnel barrier layer with said tunnel magnetoresistive effect element magnetically saturated;
• and
• at least one inductive write head element as data writing means;
• trace conductors for supplying currents to said at least one tunnel magnetoresistive effect element and said at least one inductive write head element;
• and
• a support mechanism which supports said thin-film magnetic head;
• at least one magnetic disk;
• and
• a recording/reproducing circuit for controlling reading and writing operations by said at least one tunnel magnetoresistive effect element and said at least one inductive write head element.

A testing method of a tunnel magnetoresistive effect element comprising steps of:

• applying an external magnetic field to said tunnel magnetoresistive effect element to have said tunnel magnetoresistive effect element magnetically saturated;
• measuring electric popping output voltage generated in element output voltage when a bias voltage is applied for 5 microseconds or more in a direction perpendicular to a layer surface of said tunnel magnetoresistive effect element;
• and
• evaluating said tunnel magnetoresistive effect element on the measurement result.

A manufacturing method of a tunnel magnetoresistive effect element comprising steps of:

• forming a first ferromagnetic layer and a metal layer on said first ferromagnetic layer;
• oxidizing said metal layer in an atmosphere including one, two or more of oxygen molecules, oxygen atoms, oxygen ions, ozone and dinitrogen oxide to form a tunnel barrier layer;
• forming a second ferromagnetic layer on said tunnel barrier layer to form a tunnel magnetoresistive effect multilayer;
• forming a tunnel magnetoresistive effect element using said tunnel magnetoresistive effect multilayer as a main part;
• and;
• selecting said tunnel magnetoresistive effect element by using a testing method comprising steps of:
• applying an external magnetic field to said tunnel magnetoresistive effect element to have said tunnel magnetoresistive effect element magnetically saturated;
• measuring electric popping output voltage generated in element output voltage when a bias voltage is applied for 5 microseconds or more in a direction perpendicular to a layer surface of said tunnel magnetoresistive effect element;
• and
• evaluating said tunnel magnetoresistive effect element on the measurement result.

A manufacturing method of a thin-film magnetic head comprising steps of:

• forming a tunnel magnetoresistive effect element on a slider wafer substrate by using a manufacturing method comprising steps of:
• forming a first ferromagnetic layer and a metal layer on said first ferromagnetic layer;
• oxidizing said metal layer in an atmosphere including one, two or more of oxygen molecules, oxygen atoms, oxygen ions, ozone and dinitrogen oxide to form a tunnel barrier layer;
• forming a second ferromagnetic layer on said tunnel barrier layer to form a tunnel magnetoresistive effect multilayer;
• and
• forming a tunnel magnetoresistive effect element using said tunnel magnetoresistive effect multilayer as a main part;
• cutting said slider wafer substrate into row bars on which the formed tunnel magnetoresistive effect elements are aligned;
• polishing the row bar for adjusting an MR height;
• and
• selecting said tunnel magnetoresistive effect elements on said row bar by using a testing method comprising steps of:
• applying an external magnetic field to said tunnel magnetoresistive effect element to have said tunnel magnetoresistive effect element magnetically saturated;
• measuring electric popping output voltage generated in element output voltage when a bias voltage is applied for 5 microseconds or more in a direction perpendicular to a layer surface of said tunnel magnetoresistive effect element;
• and
• evaluating said tunnel magnetoresistive effect element on the measurement result.

A manufacturing method of a thin-film magnetic head comprising steps of:

• forming a tunnel magnetoresistive effect element on a slider wafer substrate by using a manufacturing method comprising steps of:
• forming a first ferromagnetic layer and a metal layer on said first ferromagnetic layer;
• oxidizing said metal layer in an atmosphere including one, two or more of oxygen molecules, oxygen atoms, oxygen ions, ozone and dinitrogen oxide to form a tunnel barrier layer;
• forming a second ferromagnetic layer on said tunnel barrier layer to form a tunnel magnetoresistive effect multilayer;
• and
• forming a tunnel magnetoresistive effect element using said tunnel magnetoresistive effect multilayer as a main part;
• cutting said slider wafer substrate into row bars on which the formed tunnel magnetoresistive effect elements are aligned;
• polishing the row bar for adjusting an MR height;
• cutting and separating said row bar into individual thin-film magnetic heads;
• and
• selecting said tunnel magnetoresistive effect elements on said individual thin-film magnetic heads by using a testing method comprising steps of:
• applying an external magnetic field to said tunnel magnetoresistive effect element to have said tunnel magnetoresistive effect element magnetically saturated;
• measuring electric popping output voltage generated in element output voltage when a bias voltage is applied for 5 microseconds or more in a direction perpendicular to a layer surface of said tunnel magnetoresistive effect element;
• and
• evaluating said tunnel magnetoresistive effect element on the measurement result.

A testing apparatus for a tunnel magnetoresistive effect element comprising:

• a magnetic field application means for applying an external magnetic field to said tunnel magnetoresistive effect element to have said tunnel magnetoresistive effect element magnetically saturated;
• a voltage application means for applying a bias voltage to said tunnel magnetoresistive effect element for 5 microseconds or more;
• a measuring means for measuring electric popping output voltage generated in element output voltage of said tunnel magnetoresistive effect element;
• and
• an evaluating means for evaluating said tunnel magnetoresistive effect element on measured values of said electric popping output voltage ΔVP and said element output voltage ΔVS.